To meet the ever growing demands of Internet services and cloud computing, the data center industry is experiencing rapid expansion. Data centers consume billions of KWh electricity every year, and each can take hundreds of million dollars to build. Most data centers are conservatively provisioned and operated to achieve high reliability, resulting in wasted resources and high cost. In this talk, we take a holistic view of data centers and discuss opportunities and our experiences.

I will describe the key features of the Initiative launched by President Janet Napolitano to achieve zero net carbon emissions by 2025 at all 10 campuses of the UC System. The unprecedented scale and scope of this ambitious project presents some unique challenges and opportunities both for operations and for research, which I will describe and place into the context of current and future trends of energy efficiency, renewables and alternative energy technologies, as well as related economic and policy issues.

The first room temperature lasing operation of a GaN blue laser was reported in 1995 by Shuji Nakamura.  Numerous research institutions joined the race, but no one could even come close to matching the pace of Shuji.  In this talk, I will try to give you a feel for the race for blue lasers as it played out in the late 1990’s.  It can be broken down into 3 sections:

The ability to guide the development of complex materials for energy applications at multiple length and time scales hinges on a basic understanding of the physical principles  – or “design rules” – connecting their bulk properties to detailed information about their chemical composition, structure, dimensionality, and environment at the nanoscale.

The development of large-scale integrated (LSI) circuits in the 1970s led to a revolution in microelectronics with the creation of the microprocessor that revolutionized the world of computing and computer science, ultimately resulting in the Internet based world we live in today. Recent developments in microphotonics point to a similar revolution taking place in today in the development of large-scale integrated (LSI) microphotonic circuits.

In this talk, I will summarize our recent efforts on enhancing the iSIPP25G silicon photonics platform developed at imec/Ghent University through introducing new optically active materials. Our focus is on realizing lasers and power efficient modulators. Main topics I will discuss include:
(1) InP-nanowire lasers epitaxially grown on exact [001] silicon wafers using aspect ratio trapping (ART)
(2) Hybrid silicon III-V lasers realized using a BCB-based wafer bonding process

The current focus of material development in the field of organic bulk heterojunction solar cells is on donor-acceptor type low-bandgap materials, since their extended red to near-infrared absorption allows them to harvest a larger fraction of the solar illumination, allowing larger photocurrents to be potentially obtained.

We have combined ultrafast pump-probe spectroscopy with optical microscopy to study the charge carrier dynamics in semiconductor nanowires with both spatial and temporal resolution. Photoexcited charge carriers are produced at a localized spot within a single nanowire by a focused femtosecond pump pulse.

In the last decade, the constant reduction in size and the growing number of material interfaces in electronic or optoelectronic devices (such as MQW-LEDs, organic or inorganic solar cells, ...) has boosted the impact of the intrinsic disorder present at smaller scales of materials. This disorder can originate from compositional inhomogeneities, from interface roughness or from lattice defects.

For almost every action we take in our lives today, we receive the benefit of 250 years of industrial revolution, which has been arguably the most remarkable period of human history. Our global economy and our prosperity grew exponentially, and our population grew ten fold. The industrial revolution has been largely about how we sourced, distributed and used energy. It was and continues to be predominantly based on fossil energy.